Biomass-to-liquid : an anaerobic digestion and pyrolysis coupling for methanol production

The imperative to mitigate climate change necessitates a reduction in carbon dioxide (CO2) emissions. To address the pressing need to mitigate climate change, a systemic and organic approach is essential, leveraging the opportunities that arise from linking different sectors and technologies. This thesis aims to describe an Integrated System consisting of an anaerobic digester, a slow pyrolysis reactor, and an electrolyser, all with the primary objective of producing syngas. The system includes the process of converting syngas into methanol. The main scheme takes its cue from an actual plant, under construction in Denmark, by Stiesdal SkyClean, a branch of the Stiesdal company. The digestate, instead of being spread on the land, is used as biomass input to the pyrolysis reactor. Biochar is produced as a by-product, considered a carbon sink when introduced in the soil, also bringing beneficial effects to the latter. Six possible configurations have been modelled, and the pros and cons of each configuration have been investigated. For each model, the first part of the plant has been done on DNA (dynamic network analysis), an open-source software developed by DTU. On the other hand, the methanol production has been modelled on Aspen Plus. Finally, an economic analysis has been conducted, to find the most profitable configuration, including a sensitivity analysis.